The present invention relates generally to symmetric inducting devices incorporated in integrated circuits and in particular the present invention relates to an integrated circuit having symmetric inducting device with a ground shield.
Integrated circuits incorporate complex electrical components formed in semiconductor material into a single circuit. Generally, an integrated circuit comprises a substrate upon which a variety of circuit components are formed and connected to form a circuit. Integrated circuits are made of semiconductor material. Semiconductor material is material that has a resistance that lies between that of a conductor and an insulator. The resistance of semiconductor material can vary by many orders-of-magnitude depending on the concentration of impurities or dopants. Semiconductor material is used to make electrical devices that exploit its resistive properties.
It is desired to design integrated circuits in which electrical components and circuits within the integrated circuit do not interfere with each other. One method of accomplishing this is by including differential circuits. A differential circuit is a circuit that is really two circuits with opposite voltages and currents. That is, a differential circuit comprises a first circuit that produces desired voltages and currents and a second circuit that is identical to the first circuit that produces opposite voltages and currents. The opposite voltages and currents work to cancel out parasitics that naturally occur because of the voltages and currents and helps isolate the circuit from other circuits in the integrated circuit. Further discussion on parasitics can be found in U.S. Pat. No. 5,717,243, which is incorporated herein by reference.
Symmetric inducting devices are useful in differential circuits. Moreover, it is desired in the art to have a symmetric inducting device that has less resistive loss without introducing other parasitics.
For the reasons stated above and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for an integrated circuit with a symmetric inductor that has reduced resistive loss with low parasitic characteristics.
The above-mentioned problems with symmetric inductors in integrated circuits and other problems are addressed by the present invention and will be understood by reading and studying the following specification.
In one embodiment, a symmetric inducting device for an integrated circuit is disclosed. The symmetric inducting device comprises a substrate, a main metal layer and a shield. The substrate has a working surface and a second surface that is opposite the working surface. The main metal layer has at least one pair of current path regions. Each of the current path region pairs is formed in generally a regular polygonal shape. Moreover, each current path region pair is generally symmetric about a plane of symmetry that is perpendicular to the working surface of the substrate such that each current path region pair has one current path region on one side of the plane of symmetry and another current path region on the other side of the plane of symmetry. The shield is positioned between the second surface of the substrate and the main metal layer. The shield is patterned into segments. The segments of shield are generally symmetric about the plane of symmetry. In addition, medial portions of at least some segments of the shield are formed generally perpendicular to the plane of symmetry as the medial portions cross the plane of symmetry. The shield is more conductive than regions directly adjacent the shield.
In another embodiment, a symmetric transformer for an integrated circuit comprises a substrate, a main metal layer and a shield. The substrate has a working surface and a second surface that is opposite the working surface. The main metal layer has at least one pair of current path regions. Each of the current path region pairs is formed in generally a regular polygonal shape. Moreover, each current path region pair is generally symmetric about a plane of symmetry that is perpendicular to the working surface of the substrate such that each current path region pair has one current path region on one side of the plane of symmetry and another current path region on the other side of the plane of symmetry. The shield is positioned between the second surface of the substrate and the main metal layer. The shield is patterned into segments. The segments of shield are generally symmetric about the plane of symmetry. Medial portions of most segments of the shield are formed generally perpendicular to the plane of symmetry as the medial portions cross the plane of symmetry. In addition, the shield is more conductive than regions directly adjacent the shield.
In another embodiment, a symmetric inducting device for an integrated circuit is disclosed. The symmetric inducting device includes a substrate, a main metal layer and at least one current router. The substrate has a working surface and a second surface opposite the working surface. The main metal layer is positioned a predetermined distance from the working surface of the substrate. The main metal layer having at least one pair of current path regions. Each current path region pair is formed in generally a regular polygonal shape. Moreover, each current path region pair is generally symmetric about a plane of symmetry that is perpendicular to the working surface of the substrate such that each current path region pair has one current path region on one side of the plane of symmetry and another current path region on the other side of the plane of symmetry. The at least one current router is used to selectively route current from one pair of current path regions to another pair of current path regions. Each current router has an overpass and an underpass, wherein a width of the overpass is narrower than a width of the underpass.
In another embodiment, an inductor for an integrated circuit is disclosed. The inductor includes a substrate, one or more pairs of current path regions, one or more current routers and a conductive shield. The substrate has a working surface and a second surface opposite the working surface. The one or more pairs of current path regions are formed in a first metal layer. Each pair of current path regions is generally symmetric about a plane of symmetry such that each current path region pair has one current path region on one side of the plane of symmetry and another current path region on the other side of the plane of symmetry. Moreover, each pair of current path regions is formed in a generally regular polygonal shape. The one or more current routers are selectively coupled to route current from current path regions in a pair of current path regions to current path regions in other pairs of current path regions. Each current router has an overpass and an underpass. The conductive shield layer is positioned between the second surface of the substrate and the first metal layer. The shield layer is patterned into segments to decrease image currents. The segments of the shield layer are generally symmetric about the plane of symmetry, wherein a portion of most segments of shield adjacent the plane of symmetry are perpendicular to the plane of symmetry.
In another embodiment, a symmetric inducting device for an integrated circuit is disclosed. The symmetric inducting device includes a substrate, a main metal layer, a shield and a conducting halo. The substrate has a working surface and a second surface that is opposite the working surface. The main metal layer has at least one pair of current path regions. Each current path region pair is formed in generally a regular polygonal shape. Moreover, each current path region pair is generally symmetric about a plane of symmetry that is perpendicular to the working surface of the substrate such that each current path region pair has one current path region on one side of the plane of symmetry and another current path region on the other side of the plane of symmetry. The shield is positioned between the second surface of the substrate and the main metal layer. The shield is patterned into segments. The segments of shield are generally symmetric about the plane of symmetry. Moreover, the shield is more conductive than regions directly adjacent the shield. The conducting halo extends around an outer perimeter of the shield. The halo is further electrically connected to each section of shield. Moreover, the halo has at least one gap and is symmetric about the plane of symmetry. Each section of shield is electrically connected to the halo.
In another embodiment, an inducting device for an integrated circuit is disclosed. The inducting device includes a substrate, a main metal layer, a shield layer, at least one current router and one or more capacitor compensation sections for each current router. The substrate has a working surface and a second surface opposite the working surface. The main metal layer is formed a select distance from the working surface of the substrate. The main metal layer has one or more pairs of current path regions formed therein. The shield layer is positioned between the second surface of the substrate and the main metal layer. The shield layer is more conductive than regions directly adjacent the shield layer. The at least one current router couples a current path region in one pair of current path regions to a current path region in another pair of current path regions. Each current router has an overpass and an underpass. Each capacitor compensation section is electrically connected to a current path region that is coupled to an overpass of an associated current router, wherein each capacitor compensation section approximates parasitic capacitance of an underpass of the associated current router to the shield layer.
In another embodiment, a current router for an inducting device in an integrated circuit is disclosed. The current router comprises one or more overpasses to electrically connect select current path regions of the inducting device. The one or more overpasses are made from a conductive layer having a first sheet resistance. Each overpass has a first width. The current router also has one or more underpasses to electrically connect different select current path regions. The one or more underpasses are made from a conducting layer having a second different sheet resistance. Each underpass has a second different width, wherein the resistance in each overpass is approximately equal to the resistance in each associated underpass.
In another embodiment, a patterned shield layer having a plurality of segments of shield for an inducting device in an integrated circuit is disclosed. The patterned shield layer includes a plurality of conductive straps. Each conductive strap is electrically connected to a selected segment of shield to provide an alternative path of reduced resistance for the associated segment of shield.
In another embodiment, a method of forming an inductive device in an integrated circuit. The method comprising forming a shield layer. Patterning the shield layer into sections of shield that are generally symmetric to a plane of symmetry, wherein portions of some of the sections of shield are patterned perpendicular to the plane of symmetry as they cross the plane of symmetry. Forming a layer of dielectric overlaying the sections of shield. Depositing a first layer of metal overlaying the dielectric layer. Patterning the first layer of metal to from one or more pairs of current path regions that are generally symmetric about the plan of symmetry such that each current path region pair has one current path region on one side of the plane of symmetry and another current path region on the other side of the plane of symmetry.
In another embodiment, a method of forming a symmetric inducting device for an integrated circuit is disclosed. The method comprising patterning one or more pairs of current path regions in a main metal layer that overlays a working surface of a substrate of an integrated circuit, wherein each pair of current path regions are patterned to be generally symmetric about a plane of symmetry that is perpendicular to the working surface of the substrate. Forming current routers having an overpass and an underpass to selectively couple one current path region in a pair of current path regions to another current path region in another pair of current path regions, wherein a width of the overpass is formed less than the width of the underpass to approximate resistances through the overpass and the underpass.
In another embodiment, a method of forming a symmetric inducting device for an integrated circuit is disclosed. The method comprises, forming a shield layer and patterning the shield layer to form sections of shield that are generally symmetric to a plane of symmetry, wherein at least a mid portion of most sections of shield are perpendicular to the plane of symmetry. Metal straps are formed from at least one interior metal layer, wherein the at least one interior metal layer is formed a select distance from the sections of shield. Termination ends of each of the metal straps are coupled to an associated select section of shield, wherein each strap extends along the mid portion of an associated select section of shield. The method further includes forming a plurality of current path regions from a main metal layer. The at least one interior metal layer is positioned closer to the shield layer than to the main metal layer. Moreover, the plurality of the current path regions are generally symmetric to the plane of symmetry.
In another embodiment, a method of forming an inductive device in an integrated circuit is disclosed. The method comprising, forming a shield layer. Patterning the shield layer into segments of shield that are symmetric about a plane of symmetry. Forming a conductive halo a predetermined distance from shield layer, wherein the halo is formed to extend around an outer perimeter of the segments of shield. Coupling the conductive halo to each of the sections of shield. Patterning at least one gap in the conducting halo, wherein the conducting halo is symmetric about the plane of symmetry. Forming a main metal layer, the halo is positioned between the main metal layer and the shield layer. Patterning the main metal layer to form at least one pair of generally regular polygonal current path regions wherein the at least one pair of current path regions are generally symmetric about the plane of symmetry.
In another embodiment, a method of forming a current router to coupled select current path regions in an integrated circuit is disclosed. The method comprising forming a first conductive layer having a first sheet resistance. Patterning the first conductive layer to form one or more underpasses having a first width. Forming a second conductive layer having a second different sheet resistance a select distance from the first conductive layer. Patterning the second conductive layer to form one or more overpasses having a second different width, wherein the resistance in each overpass is generally equal to the resistance in an associated underpass.
In another embodiment, a method of forming an inducting device, the method comprising forming a shield layer. Forming a main metal layer a select distance from the shield layer. Patterning the main metal layer into one or more current path regions. Forming one or more current routers to couple current path regions to each other, wherein each current router having an overpass and an underpass. Forming one or more capacitor compensation sections for each current router. Coupling each capacitor compensation section to an overpass of an associated current router to approximate parasitic capacitance of an underpass of the associated current router to the shield.